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Export or Import of Table with LOB Columns (like CLOB and BLOB) has Slow Performance (Doc ID 281461.1)

Last updated on MARCH 29, 2023

Applies to:

Oracle Database Exadata Express Cloud Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.

Symptoms

An export or import of a table with a Large Object (LOB) column, has slower performance than an export or import of a table without LOB columns.

Tests done with table with CLOB and without CLOB. Both tables contained 500,000 rows of data.

                                       No CLOB      No CLOB           With CLOB
                                        DIRECT CONVENTIONAL         column
----------------------------------------------------------------------------------------
8.1.7.4.0                                0:13               0:20                      7:49
9.2.0.4.0                                0:14               0:18                      7:37
9.2.0.5.0                                0:12               0:15                      7:03
10.1.0.2.0                              0:16               0:31                      7:15
10.2.0.5.0                              1:36               2:13                      7:55
11.1.0.7.0                              0:20               0:10                      2:46
11.2.0.2.0                              1:54               2:03                    24:43

NOTE:
Above performance results should not be considered as a benchmark of the performance between different Oracle versions, as the test databases were located on different machines with different hardware, and the databases had a different parameter configuration. The main objective of these results is to give an indication of the difference in the time that is needed to export a table with a LOB column, and a table without a LOB column.

 

Changes

You recently created tables that have Large Object (LOB) columns.

 

Cause

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